1. Field of the Invention
The present general inventive concept relates to a display apparatus and a control method thereof, and more particularly, to a display apparatus and a control method thereof, in which image sticking is removed to protect a screen thereof.
2. Description of the Related Art
Image sticking is a phenomenon that a still image displayed for a long time remains on a screen while the screen displays a following image. The image sticking acts as noise in a displaying image, and may damage a display apparatus.
A display apparatus, such as a plasma display panel (PDP), a digital mirror device (DMD), etc., which processes a video signal by a time-sharing method, is susceptible to the image sticking. Particularly, when the still image has a high brightness and is displayed for a long time, a wall charge of a discharging cell allowing a pixel to emit light is not completely discharged and remains, so that the image sticking arises in the following moving picture frame. In a bad case, the image sticking may damage the discharging cell.
To prevent the image sticking from arising, there have been proposed various methods.
As an example, there is a method of decreasing the brightness of an image when the image is input as the still image. However, in this method, the brightness level is decreased without considering dark and bright regions of the still image, so that a gradation representation in the dark region is deteriorated.
Further, there is a method of slightly moving a position of the still image in up, down, left and right directions, to thereby allow the pixel to display the still image as if it is a moving picture. However, in this method, it is understood that a user still recognizes the movement of the still image even if the movement is very slight.
Yet further, there is a method of adding black/white lines to the still image, wherein adding positions are changed according to times. In this method, the image sticking is prevented because the same brightness is not applied to the same pixel for a long time. However, this method is inadequate to satisfying a user requiring a high definition display apparatus.